1 Exhibit 11 CLEAN HARBORS, INC. AND SUBSIDIARIES COMPUTATION OF NET INCOME PER SHARE (in thousands except for earnings per share amounts) THREE MONTHS ENDED NINE MONTHS ENDED SEPTEMBER 30, SEPTEMBER 30, --------------------- --------------------- 1997 1996 1997 1996 ------- ------- ------- ------- Net loss $ (786) $(1,742) $(3,652) $(5,989) Plus preferred dividends accrued 112 112 336 336 ------- ------- ------- ------- Adjusted net loss $ (898) $(1,854) $(3,988) $(6,325) ======= ======= ======= ======= Loss per common and common equivalent share: Weighted average number of shares outstanding 10,009 9,685 9,913 9,623 Incremental shares for stock options under treasury stock method -- -- -- -- ------- ------- ------- ------- Weighted average number of common and common equivalent shares outstanding 10,009 9,685 9,913 9,623 ======= ======= ======= ======= Loss per common and common equivalent share $ (.09) $ (.19) $ (.40) $ (.66) ======= ======= ======= ======= Loss per common and common equivalent share - assuming full dilution: Weighted average number of shares outstanding 10,009 9,685 9,913 9,623 Incremental shares for stock options under treasury stock method -- -- -- -- ------- ------- ------- ------- Weighted average number of common and common equivalent shares outstanding - assuming full dilution 10,009 9,685 9,913 9,623 ======= ======= ======= ======= Loss per common and common equivalent share - assuming full dilution $ (.09) $ (.19) $ (.40) $ (.66) ======= ======= ======= =======